Although LASIK, PRK, and other laser vision correction procedures have a high success rate, they don’t produce perfect vision for everyone. The results depend largely on the unique way one’s corneas respond to laser energy and how one’s eyes heal after surgery. In rare cases, patients will develop post-surgical ectasia, a condition that resembles keratoconus—a progressive eye disorder where the cornea bulges into a shape resembling a cone—but has a different origin.
Why Post-Surgical Ectasia Occurs
Some procedures e.g. LASIK involve removing corneal tissue and reshaping the corneal wall. This procedure is effective for correcting issues such as nearsightedness, farsightedness, and astigmatism, but it also inherently results in a thinner cornea. Sometimes, corneal thinning combined with internal pressure in the eye can cause expansion or distension of the cornea. In turn, this process results in irregular astigmatism with accompanying blurred and/or distorted vision. Symptoms may include glare, halos and starbursts around headlights, eye strain, and headaches.
Treating Post-Surgical Ectasia
The most effective way to treat post-surgical ectasia is with gas permeable (GP) scleral lenses.
Unlike standard contact lenses, GP lenses are rigid. They maintain their shape on the eye, where soft lenses conform to the surface of the cornea. The pliable nature of soft contact lenses makes them ill-matched to the corneal irregularities common with post-surgical ectasia. Conventional eyeglasses are no help, as they do nothing to change corneal irregularities or the vision problems those irregularities cause.
GP lenses are always superior for treating corneal irregularities. The scleral lens forms a dome or vault over the cornea itself. The space between the cornea and the back surface of a GP lens is filled with tears, which help neutralize the irregularities on the cornea’s surface. The smooth surface of the gas permebale lens then optically replaces the irregular corneal surface, effectively eliminating blur and visual distortions.
Fitting GP Lenses
Because LASIK and other laser refractive surgeries can significantly alter the shape of the cornea, fitting contact lenses on a post-surgery eye is more challenging and time-consuming than fitting lenses on a normally-shaped cornea. Because of these difficulties, special GP lens designs are often required in these circumstances.
Scleral lenses are frequently the best option for people who need non-surgical vision correction after LASIK. These large-diameter GP lenses vault over the entire corneal surface and rest on the white of the eye (the sclera). Because scleral lenses cover the entire cornea, they can be particularly effective in correcting corneal aberration and irregular astigmatism. They are also extremely helpful for treating post-surgery ectasia symptoms.
The process for fitting scleral lenses is complex. Special computerized instruments—such as corneal topographers—are usually necessary to obtain accurate measurements of the post-surgery corneal surface. These measurements allow a contact lens specialist to obtain the best possible fit and level of vision correction.
Because of these complexities, contact lens fittings after refractive surgery are typically more time-consuming and involve a higher fee than regular contact lens fittings. If you’ve never worn GP lenses before, be aware it takes longer to adapt to them than to soft contacts. You may have to wear the lenses at least part-time every day for several days before they feel completely comfortable.
Fitting GP contact lenses on an eye that has undergone refractive surgery requires special skills. Several lens modifications may be required to achieve the optimal fit, comfort, and visual acuity. At Miami Contact Lens Institute, we have the skills and experience to provide patients with a suitable GP lens fitting.
What About Hybrid Contact Lens?
Hybrid contact lenses, an alternative to GP lenses, are also useful for correcting vision after eye surgery. These lenses are designed to offer the best of both worlds: the aberration-correcting optics of a rigid GP lens and the comfortable fit of a standard soft lens.
In most cases, hybrid contact lenses are just as effective as GP lenses for correcting aberrations after vision surgery. Many patients also report they are easier to adapt to than GP lenses.
Currently, the only FDA-approved hybrid contact lenses sold in the United States are made by SynergEyes. At the Miami Contact Lens Institute, we are certified to fit SynergEyes hybrid lenses.
Corneal Collagen Crosslinking
In addition to GP lenses and hybrid lenses, Miami Contact Lens Institute recommends Corneal Collagen Crosslinking (a procedure abbreviated CXL). CXL has been shown to be an effective in halting the progressive nature of keratoconus and post-LASIK ectasia.
CXL is a minimally invasive in-office procedure intended to strengthen the cornea by creating strong bonds (crosslinks) between corneal collagen fibers. The goal of the procedure is to prevent further progression of keratoconus or ectasia. Clinical research has shown crosslinking not only stops the progression of keratoconus but also induces flattening of the cornea and may result in visual improvement. Together CXL and scleral contact lenses constitute the best combination to treat post-LASIK ectasia and keratoconus; scleral lenses help achieve clear and comfortable vision while CXL stabilizes the cornea and prevents the condition from worsening. Please contact us for more information.